Re-usable radiative thermal insulation

ABSTRACT

Commercial metalized plastic film, in the form of discarded containers or container stock, is collected, cleaned, shredded and packaged, to produce an insulating layer having a high thermal resistance, or R-value, no outgassing of volatile compounds at habitable temperatures, and multiple reusability after deployment. Each step in the sequence is designed to minimize unit cost of the process, as well as maximize the thermal resistance of the finished product. The invention largely avoids disintegration of the recycled material, and hence utilizes the embedded energy already present in the construction of the original film.

RELATED APPLICATION INFORMATION

This application claims priority from U.S. Provisional PatentApplication Ser. No. 61/192,067, entitled “Re-usable radiative thermalinsulation” and filed on Sep. 15, 2008, the disclosure of which isincorporated by reference in its entirety herein.

FIELD OF INVENTION

This invention relates to a thermal insulation for inhibiting heatlosses from interior spaces. More particularly, this invention relatesto collection, transformation, repackaging and deployment of a type ofwaste material to perform as a thermally insulating layer for aninterior space. Most particularly, this invention relates to acollection, cleaning and shredding of metallized plastic films, and thenrepackaging and deploying the shredded product as an insulating layerfor interior spaces.

BACKGROUND OF THE INVENTION

The U.S. Deptartment of Energy (DOE) recommends certain insulationperformance for attics, walls, floors, etc. For the northern U.S.climates, for example, it recommends R-49 in the attic, and R-18 in thewalls (where R-value represents thermal resistivity, which is the ratioof temperature gradient to heat flux, and is presented herein with unitsof ° F.×ft²×hrs/(Btu×in). Thicker layers of conventional fiberglassbatting (or using a blown-in version), totaling about 16 inches, canachieve the R-49 performance level. Above the ceiling rafters, there isusually no obstacle in achieving the attic targets. Walls present a fargreater challenge; since both fiberglass and cellulose insulations haveR-values of about 3 per inch, achieving R-18 requires wall cavities ofabout 6 inches in depth. Although the use of 2×6 framing, which has a 5½inch cavity depth, can approach this standard, replacement of theconventional 2×4 framing presents a prohibitively steep increase inconstruction cost, which discourages codification of this DOE guideline.

Today, R-18 is achievable in a 3½ inch wall cavity with rigid orspray-in foam insulation products, which have R-values of nearly 6 perinch. However, there are at least three significant difficulties withthis solution: (1) rigid foam board costs nearly 4 times as much perR-value as, for example, fiberglass batting, and spray-in foam is evenmore expensive; (2) the health consequence of slow volatile outgassingis a persistent concern of consumers, and contributes to slow acceptanceof this technology; and (3) from a long term EPA perspective, foamproducts have poor recycling performance.

Cellulose insulation is a present-day example of insulating materialderived from recycled products. A significant drawback is that celluloseis a biological food source, so it must be treated with insecticidesand/or anti-fungal agents before being used. Whether or not these agentsare a potential health hazard, they cannot avert biodegradationindefinitely, and are of more limited usefulness in humid climates.Despite the ecomomic advantages that cellulose enjoys over otherproducts with respect to the enormous available volume of paper to berecycled, and the small amount of additional energy needed compared tothat of fiberglass, the fact that fiberglass still maintains at least a5 to 1 market advantage underscores the disadvantages of cellulose.

Metallized polyester film, primarily polyethylene terephthalate (PET)coated with aluminum, is widely used in the food industry for containerssuch as snack food bags. Freshness is preserved by taking advantage ofaluminum's excellent diffusion resistance to oxygen and moisture. Forexample, Doritos Tortilla Chips by the Frito-Lay company alone accountfor more than 5 million bags sold each day in the United States.Considering the other products (potato chips, cookies, etc.), and othercompanies that currently utilize aluminized packaging, 20 billion bagsper year is a conservative present-day estimate, and most of the usedpackages end up in landfills. Decomposition of plastics in this lowoxygen and light-free environment has been estimated to be in excess ofa million years.

Aluminized PET (Al-PET) and other metallized polyesters (e.g.,aluminized Mylar) are also used in packaging by various otherindustries. Further, when one considers costs of the raw materials andfilm deposition processes used in manufacture, these containers add asignificant cost in embedded energy to products, making the re-use ofdiscarded bags with minimal added processing cost particularlyattractive economically. The uncoated PET used for beverage containersis already being recycled to be used, for example, as plastic textilefibers. The feasibility of doing this owes partially to theidentifiability of the waste items and their relative bulkiness perunit; on the other hand, absence of a metal co-laminate simplifies theprocess as well. The need to remove aluminum for re-use would addfurther cost for the Al-PET. Clearly there is need and incentive to findways to reuse this valuable waste as is, in an environmentally soundfashion.

SUMMARY OF THE INVENTION

The present invention introduces a new approach to thermal insulationthat is aptly labeled re-usable radiative insulation. Its insulativecapability is superior to that of fiberglass and cellulose, and rivalsthat of high-end foam products. Moreover, the environmental impact ofthe present invention compares very favorably to any of the knownalternatives; not only does the product of the invention use recycledmaterial, but as a consequence of its biological inertness, the producthas a long useful lifespan, presents no known health risks and is itselffurther recyclable.

In the present invention, discarded aluminized plastic bags arecollected, batch-cleaned, batch-shredded, and disposed into the hollowcavities of building walls to provide thermal resistance. The reflectivebehavior of aluminized plastic film enables medium- to high-performanceinsulation layers to be produced to meet current and future needs. It isdust-free after shredding, and produces no significant outgassing overtemperature ranges hospitable to life.

In another embodiment, specific volumes of the shreds are repackagedinto sealed containers in the shape of substantially flat pouches, to bedisposed into walls in a manner similar to fiberglass batting.

In another embodiment of the invention, the shreds, including containerswhich may package them, are recovered and repeatably used, withoutfurther processing other than possibly cleaning. Thus there is nointrinsic waste disposal issue with the product of the presentinvention; the property of aluminized plastic film that resistsbiodegradation, and which leads to such problems in the landfill arena,becomes an important asset in its use according to the presentinvention.

In another embodiment of the present invention, the geometry of theshreds is tailored to maximize thermal insulative capability. Shredshape (width, length, and edge patterning) and shred thickness affectthe scattering properties of the IR light energy. Thickness of theplastic also determines stiffness (springiness), and so influences thefree (unloaded) packing density of shreds.

In another embodiment of the present invention, the low specific weightand inherent springiness of the shreds results in a low free packingdensity, after which to which pressure is applied to the free-packedmass to achieve a greater packing density.

In another embodiment of the present invention, the geometry, packingdensity, and deployed layer thickness of the shreds is adjusted to beimpermeable sub-terahertz radiation, including that of cellular phonesignals and EMP (electromagnetic pulse), which is useful for buildinginformation security.

Another aspect of the invention is a high volume, batch cleaningprocess, using a mild detergent, to prepare collected waste material forshredding.

In another embodiment of the present invention, the thickness andpacking density of the shreds are such that the layer impermeable tosub-terahertz radiation, especially cellular phone signals andelectromagnetic pulse, which is useful for building informationsecurity.

Another aspect of the present invention is a supply chain for collectionof aluminized plastic film to be processed, including: (1) theenlistment and adaptation of existing community, school and wastemanagement industry recycling efforts (which already participate incellulose collection); (2) the procurement of the unused part of factoryproduction runs, such as cut-off waste and scrap; (3) production ofaluminized plastic film directly for insulation purposes, to augment thesupply from waste materials; (4) the engagement of manufacturers ofproducts packaged in aluminized plastic, as a part of their “totalsupply chain” business models.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a set of schematic illustrations to enable visualization ofthe quantitative working model that explains how the present inventionworks. FIG. 1A illustrates the model geometry. FIG. 1B is a diagram fordevelopment of a multiple reflection formula.

FIG. 2 is a cutaway drawing showing a section of an exemplary studdedbuilding wall, before and after deployment of the present invention,illustrating how shredded aluminized plastic film may be deposed intothe wall's cavity spaces to fill them with an insulating layer.

FIG. 3 illustrates another embodiment of the present invention usingcontaining pouches for the metalized plastic film shreds. FIG. 3A showsa section of an exemplary shred-filled pouch designed to fit thecavities of an exemplary studded building wall. FIG. 3B shows theinsertion of said exemplary pouch into said exemplary wall.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Although this invention will be described in terms of certain preferredembodiments, other embodiments that are apparent to those of ordinaryskill in the art, including embodiments that do not provide all of thebenefits and features set forth herein, are also within the scope ofthis invention. Accordingly, the scope of the invention is defined onlyby reference to the appended claims.

This invention provides thermally insulative layers for use in buildingsand other applications where it is desirable to prevent the transmissionof heat into or out of an interior space. An important aspect of theinstant layers is that they have higher R-value than other commercialinsulating layers of comparable cost, and may have R-value equal to, orgreater than, commercial insulators of much greater cost.

A second important aspect of the instant layers is that they may beproduced from certain common waste materials that lack biodegradability,and that have no other known intrinsic re-use value beyond theirproximate purpose. Furthermore, the energy embedded in the originalproduction of the waste materials used in the present invention islargely preserved in the instant layers. A third important aspect of theinstant layers is that they do not present environmental burdens orhazards in the present invention.

Although cellulose insulation is produced from recycled paper products,its biodegradability and moisture affinity requires special treatmentbefore deployment, limits its lifetime and climate compatibility, andprecludes its further re-use. It also has a lower R-value than theinstant layers. Foam insulation layers, either prefabricated or formedin situ (by spraying) may have higher R-values than the instant layers,but are more expensive, produce volatile outgassed contaminants while inservice, cannot be subsequently re-used, and present a waste disposalproblem at the end of their service life. Fiberglass wool is lessexpensive than foam, but has a similar end-of-life disposal problem; italso has a lower R-value than the instant layers. The generally superiorperformance of the instant layers is founded on the principles that wenow describe.

Working Principle of Reusable Shredded Insulation

The key to efficient insulation is the management of thermal infraredradiation in a non-equilibrium manner. There are three mechanisms ofthermal energy transport: conduction, convection and radiation. Contraryto conventional assumptions, conduction and convection are not dominantin insulating layers; the notion that the role of insulation isprimarily to “trap small pockets of warm air” is a popularmisconception. In reality, radiation dominates, whereby it is the roleof insulation to trap and scatter infrared (IR) photons specifically.

The presence of greenhouse gases (GHG) in the atmosphere provides anillustrative example. Any sunlight that impinges on the earth that isnot directly reflected is absorbed by it, and its energy converted intoheat. This heat re-radiates back away from the earth, nominallypropagating out into space, and cooling the earth while doing so.Passing through a less transparent atmosphere, however, the IR photonsare intercepted by GHG's such as CO₂, CH₄, etc. The vibrational modes ofthese molecules, particularly their bending modes, coincide with thethermal blackbody energy which they absorb, and then reradiate. Thereradiation of the thermal energy is in all directions, instead ofexclusively outward. Thus part of this energy is re-directed backtowards earth, causing earth to be warmer than if the thermal energy hadbeen unimpeded.

Importantly, the GHG reradiation process does not occur in a thermalequilibrium. Although the temperature of the initial thermal radiationof the IR from the earth may have been, for example, at room temperature(about 20° C.), and the temperature of the GHG molecules high in theatmosphere might be quite cold, for example, −50° C., and thesemolecules are still quite effective in scattering. In the context of thepresent invention, it is not necessary for the scattering sites (i.e.,insulator) to come into equilibrium with the incident thermal energy. Infact, ideally, we do not want it to reach equilibrium. It is better toelastically scatter or reflect this energy.

One of the limitations with conventional insulation is that it operatestoo close to thermal equilibrium, because its material (e.g., glass,cellulose, foams) is quite absorptive to IR photons. Absorption causes asmall local temperature increase, and the resulting re-radiation leadsto a net transmission forward, from the warmer side to the cooler. Eachposition within the insulation acts as a new source of thermalradiation. It is far better to reflect those IR photons by scatteringback to the source without absorption, because after an elasticscattering event, that site will remain at its original temperature andno longer radiate a net amount of energy outwardly.

The glass in fiberglass has a reflectance of about 15%, averaged overthe thermal band. Although not large, this is far greater than theorganic materials contained in foams and cellulose, whose averagethermal reflectances are in the neighborhood of 5 to 8%. In fiberglassmatting, 15% intrinsic reflectance means that 85% of the incident powerwould have to be either transmitted through the glass or absorbed by it.As it happens, in this IR thermal region, most of the 85% is absorbed,and therefore contributes to local heating. Once this local heatingoccurs, it too acts as a new radiative source to further propagate theheat energy out to the next absorption site, and so on. So although thisconcatenation retards the transmission, the process of equilibrium localheating is a fundamental shortcoming in this sort of insulator.

By comparison, a non-equilibrium insulator should have superiorinsulation performance, because new radiation sources are not producedat each scattering site. Aluminum films in the thermal IR region have areflectance of over 93%, meaning that only 7% of the energy cancontribute to any local heating. In this regard, its vastly superiorreflection performance over conventional insulation materials means thatit can be effectively used as a non-equilibrium radiative insulationproduct.

Multilayers of aluminized films have been used for years in ultrahighperformance vacuum Dewars, which perform precisely because of the highreflectivity and low absorption (and so low emissivity) of the Allayers, while the vacuum minimizes conduction and convection. Such amultilayer configuration, however, is difficult to implement in aconstruction setting. Instead, we use shredded reflective plasticmaterial to back-fill the wall cavity, as an approximation of the Dewarprinciple. In this case, it is better to think of “scattering” events ofthermal IR radiation from the random shreds, rather than reflectionevents from uniform films.

Quantitative Model

A simple quantitative model can be developed to describe ournon-equilibrium radiative insulation. Although we have indicated therelative importance of radiation over thermal conduction and convection,the latter two must be accounted for, because our product is not in avacuum. All three transport processes occur in parallel (collaterally).It happens that structural details can be assumed to allow us to(mostly) neglect the role of convection and we can gain considerableinsight by considering radiation and thermal conduction alone throughthe air medium. Our goal is to be able to mathematically describe, in ageneral way, a reflective plastic that is shredded, and hence forming adisordered array of reflectors. We start by considering two radiativeand parallel surfaces that are separated by a thermally conductivemedium. We then show how this result can be incorporated into a simplemodel that takes the disordered reflective shreds into account.

Air happens to have a fairly poor thermal conductivity (0.0256 W/m/° C.at 21° C., as given by the CRC Handbook of Physics and Chemistry, CRCPress, Boca Raton, 1980). To enable comparisons, we convert this intothe English thermal system of units used in the United States. Invertingthis conductivity to a thermal resistance, or “R-value”, leads to aresistance density or resistivity (i.e., per inch) value of 5.63°F.ft²Hr/Btu/inch. It is a rather surprising fact that this R-valuecompares quite favorably with some of the best foams, which have 5 toabout 7 per inch. Since air is such a good thermal resistor, one maywonder why we even need to displace it with other insulation. The answeris that without solid matter present, radiative and convective processesdominate: IR radiation propagates directly through air, and its fluiditysupports convective currents.

The starting point in any thermal model is the power transferred bythermal conduction,

$\begin{matrix}{{{\Delta \; P_{c}} = {A\; \kappa \frac{\Delta \; T}{\Delta \; x}}},} & (1)\end{matrix}$

where A is the cross sectional area, κ is the thermal conductivity ofthe medium, which has a temperature difference ΔT and a distance Δxbetween the hot and cold ends. This can also be expressed in terms ofthe thermal “resistance” to conduction, which is defined by R_(c)≡Δx/κ,

$\begin{matrix}{{\Delta \; P_{c}} = {\frac{A}{R_{c}}\Delta \; {T.}}} & (2)\end{matrix}$

The power radiated by any warm body (j) is given by the blackbodyexpression

P _(rad) =Aσε _(j)T_(j) ⁴,  (3)

according to its absolute temperature T, surface area A, surfaceemissivity ε_(j), and the Stefan-Boltzmann constant σ. In order tounderstand how to combine the effects of conduction and radiation, werefer to schematics of FIG. 1. In FIG. 1A, there is shown a model volume10 that is bounded by a first plate 11, having an area A, temperature T₁and emissivity ε₁, and a second plate 12, having the same area A, but adifferent temperature T₂ and emissivity ε₂. Plates 11 and 12 areseparated by a distance 13 equal to Δx.

For conduction, the plate separation 13 is an important parameter, butit is immaterial to radiation, in the limit of infinite planeboundaries. The plates emit blackbody energy by virtue of havingtemperatures above absolute zero. Thus for radiation, we consider eachplate to be a source, where plate 11 emits the rightward beam 14, havingan intensity value of I₀₁, and plate 12 emits the leftward beam 15,having an intensity value of I₀₂.

In FIG. 1B, we show diagrammatically from a side view how the energythat is first emitted from plate 11 makes multiple reflections 16 atplate 12, and re-reflections 17 at plate 11. Reflections 16 and 17 havereflectance values R₁ and R₂, respectively. Each interaction with plate12 also results in partial transmission 18 through it. Adding all ofthese terms results in an infinite series to arrive at the total amountof power flowing from plate 11 through plate 12,

T ₁₂ =I ₀₁(1=R ₂)[1+(R ₁ R ₂)+(R ₁ R ₂)²+ . . . ],

which converges to

$\begin{matrix}{T_{12} = {I_{01}{\frac{( {1 - R_{2}} )}{1 - {R_{1}R_{2}}}.}}} & ( {4\; a} )\end{matrix}$

Similarly, the net flow of power from plate 12 through plate 11 is

$\begin{matrix}{T_{21} = {I_{02}{\frac{( {1 - R_{1}} )}{1 - {R_{1}R_{2}}}.}}} & ( {4\; b} )\end{matrix}$

[We caution that our adoption of the standard optics notation R₁, R₂,T₁₂ for reflectance and transmittance not be confused with the notationwe use throughout for R-values and temperatures.] We now make use of thefact that the emissivity and reflectance are related (by definition)according to

R _(j)=1−ε_(j).  (5)

Since the incident intensities (I_(0j)) are given by Eqn. (3), Eqns. (4)and (5) can be combined to give the total net flow of energy to theright as ΔP₁₂=T₁₂−T₂₁, or

$\begin{matrix}{{{\Delta \; P_{12}} = {{A\; \sigma \frac{( {T_{1}^{4} - T_{2}^{4}} )}{( {\frac{1}{ɛ_{1}} + \frac{1}{ɛ_{2}} - 1} )}} = {A\; \sigma \frac{( {T_{1}^{4} - T_{2}^{4}} )}{\langle\frac{1}{ɛ_{12}}\rangle}}}},} & (6)\end{matrix}$

in terms of the temperatures (T_(j)) of the two plates, and where wehave defined an effective inverse emissivity <I/ε₁₂>. It should be notedthat this equation is independent of the separation between the twoplates. A similar expression is given in Solar Heating and Cooling, byJ. F. Kreider and F. Kreith (McGraw, New York, 1975), p. 17.

In order to compare with conduction processes, we would like to use thesame type of formalism for the radiation as is used in conduction inEqn. (1). In other words, we would like to consider the interior spaceto be a “black-box” of unknown processes. For our purpose, we supposethat the internal energy transfer mechanism is by a conduction process(even though we know it is a radiation process). In this way, we will beable to obtain the effective “resistance” to radiation energy transport(R_(rad)) and obtain an expression similar to Eqn. (2), i.e.,

$\begin{matrix}{{\Delta \; P_{rad}} = {{\frac{A}{R_{rad}}\Delta \; T}\; = {\frac{A}{R_{rad}}{( {T_{1} - T_{2}} ).}}}} & (7)\end{matrix}$

It is also convenient to express (T₁ ⁴−T₂ ⁴) in Eqn. (6) as

$\begin{matrix}{( {T_{1}^{4} - T_{2}^{4}} ) = {( {T_{1} - T_{2}} )4\; {T_{1}^{3}( {1 - {\frac{3}{4}\frac{\Delta \; T}{T_{1}}}} )}}} & (8)\end{matrix}$

because we would like to eliminate the ΔT term in Eqn. (7). Therefore,since we force ΔP_(rad)=ΔP₁₂, Eqns. (6) through (8) give us theeffective R-value for radiation resistance:

$\begin{matrix}{R_{rad} = {( \frac{ɛ_{1} + ɛ_{2} - {ɛ_{1}ɛ_{2}}}{\sigma \; ɛ_{1}ɛ_{2}} )\frac{1}{4\; T_{1}^{3}}{\frac{1}{( {1 - {\frac{3}{4}\frac{\Delta \; T}{T_{1}}}} )}.}}} & (9)\end{matrix}$

In Table 1, we have calculated effective radiative R-value vs.emissivity for the two thermal surfaces 11 and 12, assuming theirtemperatures are 40 C and 20 C, respectively. Values for ε₂ of about0.94 are typical of most building materials, and ε₁ of 0.1 isapproximately that of a shiny Al surface. We also see that the effectiveR-value for radiation is about 0.9, i.e., quite a bit lower than the5.63 per inch for thermal conduction through air, as noted above. Inother words, more than 6 (=5.6/0.9) times as much energy flows out froma warm body by IR radiation than by kinetic transport through collisionsby air molecules.

Since parallel conductivities are additive, resistivities addreciprocally, we have

$\begin{matrix}{{\frac{1}{R_{effective}} = {\frac{1}{R_{cond}} + \frac{1}{R_{rad}}}},} & (10)\end{matrix}$

so we find that the effective R-value for air is only about 0.78. Such alow R-value agrees with our subjective experience, but we have now shownthat the major reason for this is the simultaneous flow of substantialenergy in the form of infrared radiation.

TABLE 1 emissivity ε₁ ε₂ R_(rad) (ft²-° F.-hr/Btu) 1.00 1.00 0.858 0.940.94 0.967 0.50 0.94 1.770 0.20 0.94 4.343 0.10 0.94 8.632 0.10 0.1016.296

To check the validity of this calculation, we can derive a result thatis specified on a commercially available product. The Dow companymarkets a product called Super-Tuff-R™, which is a rigid polyisocyanatefoam insulation board having aluminum on one side, and whose basicR-value is 6.5/inch. Dow states that an additional R of 2.8 can beachieved when the Al side faces a ¾ inch non-ventilated air gap, i.e.,when no physical contact is made to the Al surface. Under thiscondition, the system R-value can be 9.3 for a 1 inch board with the ¾inch air gap. Since R_(cond)=R_(air)(0.75″)=0.75×5.63=4.22, if we useR_(rad)=8.63 from Table 1 that is appropriate for Al on one side anddrywall on the other side of the air gap, Eqn. (10) predicts aneffective R-value of 2.83.

Now that we have a solid understanding of parallel radiative platesseparated by a distance Δx in a thermally conductive medium, we willgeneralize in a simple way to the random shreds. The key is that thissame process should still be approximately valid on a local level. Thusin describing the shreds, we really only need to know the “resistancedensity” between two typical scattering sites, which is commonly knownas the resistivity (ρ), i.e.,

R _(j) ≡δx/κ _(j)=δ×ρ_(j),  (11)

where for air, ρ_(air) is 5.63 per inch (at 20° C.). Combining Eqns.(10) and (11), we obtain the effective thermal resistivity for a randompacking of reflective shreds as

$\begin{matrix}{{\rho_{effective} = \frac{\rho_{air}R_{rad}}{{\delta \; x\; \rho_{air}} + R_{rad}}},} & (12)\end{matrix}$

having units of [° F.ft² Hr/Btu/inch] and where we can understand thatδx represents an average effective separation between the shreds thatwill be governed by such things as packing density, general shape, etc.Another way to look at it is that it represents an effective scatteringlength. All of the emissive dependencies will be contained in R_(rad) asdescribed by Eqn. (9). Table 2 summarizes calculated effective thermalresistivities for different values of surface emissivities taken fromTable 1. As expected, as the scattering length approaches zero,ρ_(effective) approaches ρ_(air).

Table 2 is a summary of our non-equilibrium model, showing effectivethermal resistivity vs. scattering length (δx) for the different surfaceemissivities taken from Table 1. demonstrates that by using reflectiveshreds, medium to high performance insulation is obtained, havingR-values greater than 3 and less than 5.6, where the upper limit isimposed by the thermal resistivity of air, which is 5.63 per inch at 20°C.

TABLE 2 ε₁ 0.94 0.50 0.20 0.10 0.10 ε₂ 0.94 0.94 0.94 0.94 0.10 R_(rad)0.967 1.770 4.343 8.632 16.296 δx (in.) ρ_(effective) (° F. in⁻¹ ft² HrBtu⁻¹), i.e., R per inch 0.000 5.63 5.63 5.63 5.63 5.63 0.063 4.13 4.705.21 5.41 5.51 0.125 3.26 4.03 4.85 5.21 5.40 0.250 2.29 3.14 4.25 4.845.19 0.500 1.44 2.17 3.42 4.25 4.80 0.750 1.05 1.66 2.86 3.78 4.47 1.0000.83 1.35 2.45 3.41 4.19

Preferred Embodiments of the Invention

All of the preferred embodiments of the instant invention share animportant first common element of collection of raw material accordingto a supply chain business model, and said model is included as part ofthe claims. Aluminized plastic film for the instant invention issupplied at least three different sources. A first source is the wastestream of discarded packages, where it appears in increasing amounts,and is becoming a landfill space allocation problem, due to its slowbiodegradation. To collect from this source, enlistment of volunteerefforts are used, coupled with two types of industrial cooperation: (1)participation by waste collection companies in the form ofclassification and separation by customers as a recyclable waste type,and (2) participation by product suppliers who use aluminized plasticfilm packages, in the form of cash incentives for the return of theemptied packages, with the cost either absorbed as a community serviceor compensated in part by the producer of the instant invention. Asecond source of aluminized plastic film is scrap incurred in theprocesses of manufacturing said film itself, fabrication of packagesfrom said film, filling said packages with salable products, ordistribution of said products. In the sequence of these activities,there is a considerable amount of scrappage, resulting from cut-offwaste, process control, and product control, for examples. In thesecases, it is advantageous to coordinate with whole product supply chainsof vendors. A third source of aluminized plastic film is the manufactureof the film specifically for the purpose of production of thermalinsulation layers according to the instant invention. Although thissource lacks the environmental synergy of the waste sources, it servesto augment what could become a limited supply, and also removes thecosts of cleaning and shredding. Said avoidance of shredding may beeffected by drawing the plastic film into narrow strips that areequivalent to shreds, and applying the metal coatings to the strips.

In a first embodiment of the instant invention, aluminized plastic filmcollected from the public waste stream is subjected to cleaning ofextrinsic material that would preclude its successful processing ordeployment according to the invention. Said cleaning is performed in abatch process, consisting of (1) a first step of agitation of aplurality of Al-plastic packages in a vat of water and a mild detergent;(2) a second step of rinsing in a sequence of tanks, said rinsing usingeither a cascade or a dump configuration; and (3) a third step ofdrying, using forced air and tumbling configurations, for example.

In a further embodiment of the instant invention, dry aluminized plasticsheets and packages are cut into narrow strips by a shredding process.Said shredding process may be effected using a dedicated paper-shreddingmeans, or another design. Means may be employed to prevent buildup ofsoftened plastic on the cutting edges.

A particular preferred embodiment of the instant invention isillustrated in FIG. 2, wherein the invention serves as insulation for astudded building wall. FIG. 2A shows a cutaway of a section 20 of awall, with two sheets 21 separated by stud spacers 22. Aluminizedplastic film shreds 23 that may have been collected, cleaned andshredded according to embodiments described herein, are shown beingplaced into a hollow cavity space 24 formed by the structure. FIG. 2Bshows a cutaway of the same section 20 at a later time, wherein cavityspace 24 has been completely filled with shreds 23 to a desired packingdensity, to form a collective layer 26, which is also a thermallyinsulating layer.

Another preferred embodiment of the instant invention is illustrated inFIG. 3, wherein the invention serves as insulation for a studdedbuilding wall. FIG. 3A shows a pouch 36 that is filled with a pluralityof aluminized plastic shreds 33 to a desired packing density, and thensealed. The pouch 36 has substantially a shape that enables it, whenfilled, to fit into, and substantially conformally fill, a cavity spacefor which it is intended. FIG. 3B shows a cutaway of a section 30 of awall, with two sheets 31 separated by stud spacers 32. Pouch 36, filledwith shreds 33, is shown being inserted into the hollow cavity space 34formed by the wall structure.

In a preferred embodiment, the pouch 36 of FIG. 3 is constructed ofmetallized plastic film.

In a further preferred embodiment, the embodiments shown in FIG. 2 andFIG. 3 are combined, so that the pouch 36 is first inserted into cavityspace 34, and then loose shreds 23 may be added to occupy remainingunfilled regions in the cavity space 34.

In a further embodiment, loose shreds of aluminized plastic film in FIG.2 and FIG. 3 are blown into the hollow cavity spaces 24 and 34 in asimilar fashion as is cellulose insulation or loose fiberglassinsulation.

In another preferred embodiment, at the end of the life of a buildinginsulated according to the instant invention, loose aluminized plasticshreds are removed from the walls by a suitable vacuum apparatus, andintact pouches are extracted, the recovered shreds and packages arecleaned and repackaged, if appropriate, and used in another building.

Those skilled in the art will appreciate that the methods and designsdescribed above have additional applications and that the relevantapplications are not limited to those specifically recited above. Also,the present invention may be embodied in other specific forms withoutdeparting from the essential characteristics as described herein. Theembodiments described above are to be considered in all respects asillustrative only, and not restrictive in any manner.

1. A method for providing thermal insulation comprising: obtainingmetalized plastic film; shredding said metalized plastic film; disposingsaid shredded metalized plastic film between a first surface and asecond surface.
 2. The method of claim 1, wherein said first surface andsaid second surface form a portion of a boundary, said boundaryenclosing or partially enclosing a volume space.
 3. The method of claim2, wherein said volume space is a building or a room within saidbuilding.
 4. The method of claim 2, wherein said volume space is aportable living space.
 5. The method of claim 2, wherein said volumespace is a vehicle.
 6. The method of claim 2, wherein said volume spaceis a container.
 7. The method of claim 1, wherein said metalized plasticfilm is a waste product.
 8. The method of claim 7, wherein saidmetalized plastic film waste is a discarded package of a perishablecommercial product.
 9. The method of claim 7, wherein said metalizedplastic film waste is the cut-off waste or scrap waste incurred in themanufacture of metalized plastic film and packages for perishable orlight-sensitive products.
 10. The method of claim 7, wherein saidmetalized plastic film waste is cleaned before said shredding.
 11. Themethod of claim 7, wherein said obtaining includes collecting saidmetalized plastic film waste from a recycler.
 12. The method of claim 7,wherein said obtaining includes collecting unused waste and scrap frompackage manufacturers.
 13. The method of claim 1, wherein said metalizedplastic film is shredded into strips having widths of between 1millimeter and 1 centimeter and having random lengths.
 14. The method ofclaim 1, wherein said metalized plastic film is shredded into stripshaving selected widths and selected lengths according to predeterminedmathematical distribution formulae.
 15. The method of claim 1, whereinsaid metalized plastic film is aluminized plastic film waste.
 16. Themethod of claim 1, wherein the space between said first surface and saidsecond surface is substantially filled with said metalized plastic film.17. The method of claim 1, further comprising adjusting the amount ofsaid metalized plastic film disposed between said first surface and saidsecond surface to achieve a predetermined thermal resistance.
 18. Themethod of claim 1, wherein said disposing includes placing said shreddedmetalized plastic film in a pouch and disposing said pouch between saidfirst surface and said second surface.
 19. A thermal barrier,comprising: a first surface layer and a second surface layer, with ahollow space in between; and an insulating material disposed within saidhollow space, wherein said insulating material comprises shreds ofmetalized plastic film.
 20. The thermal barrier of claim 19, whereinsaid thermal barrier is a wall.